Python 3

In 1913 Bohr presented the first atomic model, where electrons orbit around a positively charged nucleus at the centre of the atom. In the case of hydrogen, which only has one electron, the circular orbit of radius rn is defined as: m e* where the reduced Planck constant is 1.05457 103* J s, the vacuum permittivity-8.854 10-12 C1 (N m2), the mass of the electron me-9.10938 1031 Kg and the electron charge e-1.6022-10-19 c. The integer n is a quantum number (n 1,2,3.). The energy of the electron (including kinetic energy and potential energy) is given by: where rn is the orbital radius given in formula (1). In classical physics, an electron in orbit should emit electro-magnetic radiation, loosing energy until it falls down onto the proton. Bohr proposed that the electron can stay in circular orbits at specifically quantized energies without losing energy